What to check first

Open the dongle in the middle of the cable to check if the profilic chip is used. You need to check the color coding of the wires. Best would be to just leave the dongle open. In my example here we have the color coding for the FutureDial-Cables. If you have a different one check http://www.nslu2-linux.org/wiki/HowTo/AddASerialPort for the color coding.

Open the phone connector of the cable

you can slide out all the cables ends out of the connector. Use flat nose pliers.

Prepare the phone sync cable

In this picture: Green is GND, Yellow is RX (as in "data entering the LSPro") and Orange is TX. The not connected terminal is VCC.